Shrieking in terror, Lefley had to be dragged to the gallows — still protesting her innocence. She’d never admitted to the crime, and they’d never been able to show that she purchased any arsenic.

There was some thought that William may have committed suicide: he’s known to have attempted it once before. But the more outlandish defense hypothesis that some unknown third party might have snuck in and poisoned the morsel gained unexpected credence in 1893 when a farmer made a deathbed confession to having done just that … over a wholly unrelated-to-Mary financial grudge.

* Mary Lefley knew the last notorious Lincolnshire poisoner, Priscilla Biggadyke — who hanged for poisoning off her husband in 1868. “They are hanging me for my past!” Lefley exclaimed when she was convicted. (Priscilla turned out to be innocent, too.)